The Royal Thai Navy seized two more Vietnamese fishing boats and arrested 30 crewmen for illegally working in Thai waters.
Navy officials announced the capture of the two numbered boats May 24. The two 18-meter vessels had 17 and 13 crewmen on board, respectively.
Rear Adm. Wasan Boonuang said the boats were spotted by navy patrols May 21 about 150 nautical miles south of Koh Chuang.
He said an investigation has pointed to signs that Thai companies are illegally selling fishing concessions and equipment to boat operators in neighboring countries.
In the past eight months, eight Vietnamese boats have been seized and 198 fishermen arrested and deported.